JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismCHAPTER 8: ELECTROMAGNETISM8.1: MAGNETIC EFFECT OF A CURRENT-CARRYING CONDUCTORElectromagnets current 1. Conductor is a material that can flow .. electricity 2. Elecomagnetism is the study of the relationship between .and magnetism .. Electric fieed by electrically charged objects. magnetic fields 4. A bar magnet produces the around it. Draw the pattern of the magnetic fields produced around a bar magnet belo Show the deflection of the pointer of the compasses .NS6. Magnetic fields also can be produce by an electric current in a wire. temporary 7. Electromagnet is a magnet. It is made by winding a coil of insulated wire round a soft iron core.1JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: Electromagnetism8. Using the diagram, complete the steps to switch on the magnetism effect.Soft iron core switch Insulated wire switchSoft iron coreDC supplyDC supplyInsulated wirepinspinsSwitch is closedCurrent flowsMagnetic filedSoft iron core is magnetisedAttracts pinsMagnetic Field due to a Current in Straight Wire1. Using Right-hand Grip rule, draw the direction of current flows and pattern of magnetic fields formedDirection of magnetic fields2. Right-hand Grip Rule states that the thumb of the right hand points to the direction ofmagnetic fields current flow and the other four curled fingers points to direction of its .2JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: Electromagnetism3. Draw the same patterns from the top views as follows together with the direction shown by the compasses.into Means that a wire carrying current .. the plane of paper out Means that a wire carrying current ... of the plane of paperExercise 8.1 1. Two small plotting compasses P and Q are placed near a long straight wire carrying a current as shown.Show the directions shown by the pointers of the compasses3JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: Electromagnetism4. In the diagram below, the compasses are put under the conductor. Draw the direction shown by compasses and what happen if the compasses are put on the conductor?Magnetic Field due to a Current in a Circular Coil5. Draw the direction of current flows and pattern of magnetic fields formed. 6. The direction of magnetic field also can be determine using the RightHand Grip Rule.4JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismMagnetic Field due to a Current in a Solenoid7. Solenoid is combination of coils of wire wounded around on some surface or wounded around an iron core. 8. Draw the direction of current flows, pattern of magnetic fields formed and direction by the compasses. 9. To check the poles formed, see from beside of the solenoid. If the current flow is South clockwise, the polarity on that side is but, if the current flow is North anti-clockwise, the polari on that side is NSFactors that affects the strength of an electromagnet 10. To study this, we need to carry out experiments as follows. The higher the number of paper greater clips attracted to the solenoid shows the ...the strength of that electromagnet.Iron core Paper clips5JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismManipulated Number of turns Current Types of coreResponding Number of paper clips attracted Number of paper clips attracted Number of paper clips attractedFixed Current, types of core Number of turns, types of core Number of turns, CurrentFactors that affects the strength of an electromagnet 11. As a conclusion, fill the table below Factors Conditions Number of paper clips attracted Number of turns Electric current Use of normal iron-core Use of soft-iron core -nilAffects on the strength of electromagnetic fieldsApplications of Electromagnet 12. There are many applications of electromagnets. Label and describe the figure of each apparatus stated in the table below with its simple work-frame. 1) Electric bells batteries switch 1. When the switch is closed, the current flow will magnetized the soft-iron core springs 2. The soft iron armature is pulled toward electromagnet and hit the gong 3. At the same time, the contact will open and stop the current flows. No electromagnet. soft-iron core contact 4. The spring mechanism brings the armature back to its original position soft-iron armature gong 5. The contacts close again and similar process is repeated.6JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: Electromagnetism2) Electromagnetic Relays1. When the switch A is closed, a small current flows in input circuit will magnetized the soft-iron core 2. The soft iron armature is attracted toward electromagnet 3. At the same time, the spring contact closed 4. A large current flows to high voltage circuit to operate the electricalsoft-iron coreapparatus. to high voltage circuit3) Telephone earpieces 1. A varying current received from the Alloy diaphragm caller in telephone line 2. The varying current passes through solenoid and magnetized the soft-iron core 3. The electromagnet varies in magnetic Soft-iron core strength according to the verifying current 4. The alloy diaphragm will attract to Permanent magnet solenoid electromagnet by varying force 5. Sound produced as compression and rarefaction of air particles7JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: Electromagnetism4) Circuit breakers automatic switch to Its operate as breaks circuit to open when t becomes too large 1. When the current becomes high (ex: shuddenly 2. The iron catch is pulled toward electromagnet 3. The spring pulling apart the contacts 4. The circuit will break and the current spring contacts flows stop immediatelyfrom main supplyto household appliances5) Lifting Magnet move heavy objects or Its function to steel from place to place he surface will produces a stronger magnetic field 2. When the current is switched on, the soft iron core is magnetized to become a very powerful magnet Noth pole 3. Its lifts up iron and steel 4. When the crane has moved to new South pole location, the current is switched off and the soft-iron core is demagnetized 3. The objects will fall8JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismExercise 8.1.2 1. A magnetic field is produced by the current in a long straight wire. The strength of the magnetic field increases if. A B C The magnitude of the current increases The distance from the wire increases The length of the wire increases2. Which of the following is true about the magnetic field produced by a current in a flat circular coil?. A B C D It is uniform inside the coil It is the weakest at the centre It is the strongest at the centre There is no magnetic field outside the coil3. What is the effect of placing a piece of soft iron core inside a solenoid carrying current? A B C The resistance of the solenoid decreases The current in the solenoid increases The magnetic field becomes stronger4. An electromagnet is used in these apparatus except A B C D a compass an a.c dynamo a moving coil ammeter a telephone earpiece5. Which electromagnet is the strongest? A B C D+2V-+2V-+4V-+4V-9JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: Electromagnetism3.2: Force Acting on a Current-carrying Conductor in a Magnetic Fields 1. If a current-carrying conductor is placed in a magnetic fields as shown in the experiment, the force conductor will experiences a ..Magnet C-Shape ironFreely conductor Long conductorPower Supply2. Draw the combination (called catapult field) of two electromagnetic fields below and show the direction of movement of the conductor.NSNS+=3. Fleming's left-hand rule can be use to determine the direction of the force acting or the motion of the conductor.First Finger ( Field )Thumb (Thrust force )NCentre Finger ( Current )10JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismEffect of Two Parallel Current-carrying Coils in a Magnetic Field 4. If two current-carrying conductor is placed in a magnetic fields as shown in the experiment, repel attract the conductor will experience or .. force between them. 5. Compam for current with opposite direction flows in two parallel conductor below:repel The two conductor will .. to each other 6. Complete the diagram for current with same direction flows in two parallel conductor below:attract The two conductor will .. to each other 11JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismTurning Effect of a Current-carrying Coil in a Magnetic Field 7. Consider a current-carrying coil ABCD placed between the poles magnet as shown in the figure below. upward 8. As the current flows through the coil from A to D, an ... (1) force acts on the downward arm CD whereas a (3) force acts on the arms AB according to Fleminft Hand rule. N Coil S B 2 3 Magnet D current commutator C1 Carbon brush 4 AElectrical energyKinetic energy9. Draw the catapult field formed and draw arrows to show the movement of arms AB and CD.FN CDSABF12JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismDirect Current Motor 10. Complete the four stages of the motion of DC motor belowNCoilS1 Acurrent00 Degree : Current flow : Yes / No Through carbon brushes to the ... cArm CD : anti-clockwise Rotation : .B 2 D C4 3NCoilS900 Degree : Current flow : Yes / No Open circuit at carbon brushes ...currentleft Arm CD : anti-clockwise Rotation : due to inertia .NCoilS1800 Degree : Current flow : Yes / No through carbon brushes ..... upwcurrentdownward Arm CD : Rotation : anti-clockwise 13JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismNCoilS2700 Degree : Current flow : Yes / No Circuit broken at carbon brushes ...currentleft Arm AB : . right Arm CD : Rotation : anti-clockwise due . toComparison with Alternating Current Motor 11. Complete the diagram of AC motor below:a.c supply14JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismFactors that affect the speed of rotation of an electric motor 12. The magnitude of force acting on a conductor in a magnetic increases by: i. Increasing the current flow ii. Stronger magnet used 13. In conclusion, the speed of rotation of the coil also can increased by: Increasing the current i. Using a stronger magneber of turns on the coils iii. .Moving Coil AmmeterThe angle of deflection is directly proportional to the current flows in the coil The hair spring will restore the pointer back to its original position. The force acting causes the coil to rotate and lead the pointer to the deflectionWhen current flows in moving coil, magnetic field of radial magnet will interacts with magnetic field produce by the coil15JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismExercise 8.21. The motion of a conductor carrying current in an magnetic fields can be determine by A Right hand Grip Rule B Fleming's Right Hand Rule C Fleming's Left Hand Rule D Direction of current flow A4. The function of the commutator in a d.c. motor is to reverse the current in the coil atevery half rotation B to enable the coil to be in electricalcontact with carbon brushes C to prevent the wires from entangling2.N5. A moving coil-ammeter is less sensitive ifNSA B Cthe hair spring is harder the magnet is stronger the scale is shorterA current carrying wire is in between the poles of a magnet. The direction of the force on the wire is A North South B D East West C 6. Choose the best pattern formed.3. Two parallel wires are carrying equal currents in opposite directions. Which diagram shows the forces F on the wires? A B F F C F F F D F F F16JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: Electromagnetism3.3: Electromagnetic Induction solenoid 1. As we know, a steady magnetic field can be produced by a or wire carrying electric current . 2. When we move a ct flow is in a magnetic field, an induced e.m.f (electromotive force) is produced. induced current 3. An flows through the conductor and this phenomenon called eetic induction 4. So, electromagnetic induction requires relative motion betweenthe coil to produce an induced current. 5. Complete the table below as experiment data for the diagram below:Induced e.m.f by a moving conductorGAction The wire is moved upwards The wire is moved downwards The wire is move horizontally Magnet is moved upwardsObseravtion Galvanometer deflect to left Galvanometer deflect to right No deflection Galvanometer deflect to rightInference Current flows in wire Current flows is reversed No current flows Current flows is reversed17JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: Electromagnetism6. Fleming's Right-hand rule can be use to determine the direction of the induction current produced. Thumb ( motion )First finger ( Field )Center finger ( induced current )Induced e.m.f by coilMagnetic field lines are being cut. Current inducedNo deflection on the galvanometer No current is inducedMoving the coil towards a magnet also induces current Current induced in opposite direction18JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismLenz's Law 7. Lenz's Law also can be use to determine the direction of induced current produced. 8. Lenz's Law states that the direction of the induced e.m.f is such that its magnetic effects oppose always .the change producing.When the N pole is moved towards the coil, end of coil becomes N pole.When the N pole moved away from the coil, end of coil becomes S pole.Faraday's Law of electromagnetic induction directly proportional 9. Faraday's Law states that the magnitude of the induced e.m.f. is .. to the rate of change of magnetexperienced by the conductor. 10. The magnitude of the e.m.f in a wire increases when: The wire is moved faster i. A stronger magnet is used ii. ased iii. ... 11. The magnitude of the e.m.f in a coil increases when: The ren magnet and coil is increased i. . The number of turns on coil is inccreased iii. ....19JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismApplications of electromagnetic induction 12. A generator is basically the inverse of a motor. There are many coils of wire wound that can falling water rotate in a magnetic field. The axle is turned by some mechanical such as .., steam .13. The dc generator and ac generator make use of electromagnetic induction to produce output voltage DC GeneratorSplit rings commutator20JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: Electromagnetism14. Draw the graph of output current from the dc generator above.When coils is at its horizontal position 900 2700 ...........................

Change of rates of magnetic flux is maximum Induced e.m.f is maxsimum

When coils is at its vertical position 00 1800 .. 3600 2700 No changes of magnetic flux No e.m.f is induced21JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismAC Generator15. Draw the graph of output current from the ac generator above16. The magnitude of the output voltage increases when: Number of turns of the coil is increased iv. . The strength of the permanent magnet is increased 22JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismWhen coils is at its horizontal position 900 2700 ...........................

Change of rates of magnetic flux is maximum Induced e.m.f is maxsimum

When coils is at its vertical position 00 1800 .. 3600 2700 No changes of magnetic flux No e.m.f is induced23JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismAlternating and direct current (a.c/d.c) 17. Complete the table of comparison below. AC Current Graphs Current, I/A Current, I/A DC CurrentTime, t/sTime, t/sCurrent, I/ACurrent, I/ATime, t/sTime, t/sDirection variable constant Examples of sources and symbols 1. ac generator 2. dynamo 3. home plugs 1. dc generator 2. dry cells 3. electrolyte cells+-24JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismExercise 8.31. Which of the following is an example of induced magnetism? A. A compass needle pointing north B. A north pole attracting iron fillings C. A north pole repelling a north pole D. A coil of a motor tuning in magnetic field 4. Which of the following represent the output voltage of an a.c generator? A.2. The diagram shows a coil in magnetic field. If we want to make a a.c generator, what should to be connected to X and Y? A. d.c. supply B. Slips rings C. Soft-iron core D. Split rings commutatorB.C.D.3.25JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: Electromagnetism3.4: Transformers 240 V 1. In Malaysia, our electricity for domestic supplied at a voltage of a.c. 2. However, most of home appliances at home use lower than or higer than 240V. laptops televisions 3. Transformers are found in many devices such as ., ., mobile phones .. and etc. larger small 4. The main use of transfo . one or vice-versa.Operating principle of a transformer 5. Complete the diagram below Laminated soft-iron core INPUT OUTPUTPrimary coilSecondary coilSymbol of transformer magnetic field 6. When an alternating current flows in primary coil, and .. is produced in the soft iron core. secondary 7. Magnetic flux link . coil and will cut the magnetic fields lines. current 8. The secondary coil experiens the rate of change of magnetic field and . is induced in secondary coil. (induced e.m.f) collapses 9. When the current in primary coil decreases, the magnetic field will and again cut the secondary coil. 10. An e.mf acting in the opposite direction is induced in the secondary coil. alternating e.m.f 11. Hence, an .. of the same frequeis induced in the secondary coil. ratio 12. The output voltage is depends on the . of number of turns of primary and secondary coils. 26JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismStep-up and step-down transformers13. The relationship between the voltages and the ratio of the turns in primary and secondary coils can be write as below. Primary voltage Secondary voltage Vp Vs= =Number of turns in primary coil Number of turns in secondary coil Np NsORVp Np=Vs Nsgreater 14. If Ns is greater than Np, then Vs is than Vp. The type of transformer is step-up transformer . less 15. If Ns is less than Np, then Vs is than Vp. The is step-down transformer . 50 16. For example, if the turns ratio is 1:50, the outptage is stepped up .. times.Step-down transformerStep-up transformer17. If we consider an ideal transformer, there is no loss of energy.Power supplied to the primary coil VpIp= = =Power used in the secondary coil VsIs Is Ip=Vp VsIs IpNp NsComparing with the transformer equation27JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismEnergy losses in a transformer 100% 18. As we know, an ideal transformer has .. effiency. less than 19. But in practice, the efficiency of a tranformer is .. 100%. 20. The effiency of a transformer is expressed as follows:

Pout 100% Pin VsIs 100% VpIp21. Complete the table below: Type of losses Eddy current Changing ofCauses magnetic field induced current

Way to reduce Use laminated corein soft iron core Eddy currentproduced and generate heat Use lowHeat loss Asthe number of turn increases, theresistance copperresistance of conductor also increases. Heatwiresproduced by electrical energy to opposethe resistance The core is Use soft-iron ItHysterisismagnetized and demagnetizedcorealternately due to a.c current in primary coil Energy lossis able to be magnetized andas heatdemagnetized easily ProperFlux leakage Leakage ofmagnetic flux in the primary coilcore design28JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismExercise 8.4 4. The number of turns between each pair 1. Soft iron core is used as the transformer core because A. Soft iron core has low resistance B. Soft iron becomes a permanent magnet C. Soft iron is easily magnetized and demagnetized D. Soft iron is better conductor than steel A. P and Q B. Q and R C. R and S D. P and R of output terminals of a transformer is shown in the diagram. Between which terminal the output is 12 V?2. Which of the following is correct about step-down transformer A. The output voltage is higher than input voltage B. the output power is greater than input power C. The output current is greater than the input current5. When primary coil of an ideal transformer is connected to 12 V a.c supply, the current is 2.0 A. If the output voltage is 400 V, what is the3. All the four transformer given below have the same input voltage. The number of turns in the primary coil and secondary coil are N1 and N2. Which has the highest output voltage? N1 A B C D 12000 60 6000 1200 N2 24000 1200 2000 200current in secondary coil? A. 0.06 A B. 0.60 A C. 6.67 A D. 66.7 A6. A transformer only can work with A. d.c supply B. a.c supply C. dry cells D. electrolyte cells29JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: Electromagnetism3.5: Generation and Transmission of Electricity Sources of Energy 1. The generation of electricity comes from many sources such as : Hydro a. Gases b. ...Transmission of Electricity d.c 2. Electricity can be supply either from .. or a.c source. 3. The circuit diagram below shows a sample of the transmission of electricity from d.c source. Draw the current flow on the circuit diagram.bulba.c 4. The diagram below shows a sample of the transmission of electricity from source.30JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismNational Grid Network pylons 5. National Grid Network is a network of underground cables or which connect all the power stations and substations for the whole country. 6. This network starts at electrical power plant like Chenderoh Lake Power Station which is hydroelectric power station, and end at our houses. 7. Complete the diagram below by showing the cables of transmission and suitable users.400 kVtransmission 132 kV 33 kVHeavy industry11 kVLight industry450 V240 VMy houseBuildingsStep-up transformerStep-down transformerStep-down transformers33 kV Power plant 8. Electrical energy is transmitted from the power station to the consumer using long transmission cables. heat 9. This will bring to power loss as energy. Power loss can be calculate as follow:Pheat I R2I = current flows in the cable R = resistance of the cable31JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: Electromagnetism10. The power loss can reduce by: resistance i. Reducing the of the cables increasin. Reducing the current or . the voltage in the cable.Renewable energy 11. Energy plays a very important role in economic development but the reserves of fossil fuels such as oil and gas are very limited. 12. Hence, there is modern trend of the nations that is to harness the renewable energy. 13. Renewable energy sources are continually replenished naturally means they are sustainable. 14. Give the example of renewable energy: Hydroelectric i. Solar ii15. Give the example of non-renewable energy: Fossil fuel such as: i. .. Oil a) 16. Give the benefits of using the renewable energy to our nation: Avoid depletion of fossil fuels i. Cleaner sources for little pollution ii. - End of Chapter 8 -32JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismExercise 8.51. Which of the following is not a renewable energy source? A. Wind B. Solar C. Coal D. Biomass5. In the transmission of electricity, the most effective mean to reduce power loss in the transmission cable is by A. Using copper cables B. Transmission at high voltage C. using alternating current D. Using thick cables2. The major source of energy for electrical generation in Malaysia is A. Natural gas B. Wind C. hydro For question 6 and 7 6. A power station generates 500 kW of power at 600 V. An ideal transformer steps up the voltage to 132 kV for transmission. 3. Which of the following is an advantage of using wind energy for generation of electricity? A. Its available all the time B. Its easy to use C. Its cheap to use D. It's a renewable energy What is the ratio of the number of turns in the secondary coil of the transformer to that in primary coil? A. 1:22 B. 22:1 C. 1:220 D. 220:14. Which of the following is an advantage of National Grid Network? A. Electrical power breakdown can be countermeasure immediately B. Loss of power can be reduce C. Its using less cables D. It's a renewable energy7. If the resistance of 1 km of the cable is 2 , what is the power loss from each km length of cable? A. 3 W B. 16 W C. 26 W D. 29 W33JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismReinforcement Chapter 8 Part A: Objectives Questions 1. Which diagram best shows the pattern of field lines around a bar magnet? A. E compass B. 3. Refer to the diagram above, when the switch is close, the pointer of the compass will point to C. A. Stay at North B. East C. West D. D. Vibrate at its place wire cardboard W N.4. A straight wire carrying a current produces a magnetic field. Which diagram shows the correct shape of the field? 2. Which materials are suitable to make the core of an electromagnet? Core of an electromagnet A B C D Iron Steel Wood Cuprum A.34JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismB.A. Change the direction of the current B. Move the poles closer C. Send a smaller current through wire D. Use stronger magnetC.6. When electricity is transmitted over long distances, energy is wasted. How can the wasted energy be kept as small as possible?.A. Keep the current in the transmission lines D. as large as possible B. Keep the power supplied to the transmission lines as large as possible C. Keep the resistance of the transmission.lines as large as possible D. Keep the voltage supplied to the transmission lines as large as possible5. A student carries out an experiment to see the effect of a magnetic field on a wire carrying a current. The wire moves upwards as shown. What should the student do to make the wire move downwards?7. The diagram shows a transformer35JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: Electromagnetism.What is the voltmeter reading? A. 1.2 V B. 12 V C. 120 V D. 1200 V10. The diagram shows a solenoid connected to a sensitive voltmeter. Which of the following would give a zero reading on the voltmeter?8. Which two electrical quantities are measured in volts? A. current and e.m.f B. current and resistance C. e.m.f and potential difference D. potential difference and resistance A. Holding the magnet stationary inside the 9. The figure shows an electromagnet. solenoid B. Moving the magnet away from the solenoid R C. Moving the magnet towards the solenoid D. Moving the solenoid towards the magnet The strength of the magnetic field can be increase at point R by I increasing the number of turns of the coil II reducing the resistance of the rheostat III bringing the electromagnet closer to P A. I and II only B. I and III only C. II and III only D. I, II and II only A. 50 V B. 100 V C. 200 V D. 800 V.11. The diagram shows a transformer with an alternating voltage of 100 V applied to the primary coil. What is the output voltage?36JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismA. 12.5 V 12. Which graph shows the output voltage from a simple a.c. generator? A. B. 50.0 V C. 175 V D. 200 V.14. Two circuits are set up as shown. The iron B. rods are placed close together, and are free to move.C. What happens to the size of the gap at X when switch S is closed? D. A. It decreases B. It decreases then increases C. It increases D. It does not change.13. A transformer has 50 turns on its primary coil and 100 turns on its secondary coil. An a.c. voltage of 25.0 V is connected across the primary coil. What is the voltage across the secondary coil?15.NPQRS is a cuprum wire put horizontally on a table. X and Y are two compasses put on the wire. What will happen to the compasses when switch S is closed?37JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismA. Both compasses point to East B. Both compasses point to West C. Both compasses pointer unchange D. Compass X pointer unchanged but compass Y point to East.18. Electromagnetic strength can be influence by these factors except A. Magnitude of current B. Direction of current flows C. Number of turns D. Types of core used16.For questions 19 and 20 In a model of the transmission of electricity, electrical power of 36 W is generated at 12 V and transmitted using cables of total resistanceDiagram shows an electromagnet PQR. The poles for PQR are2.0 . 19. What is the current in the cable? A. 2.0 AA B C DP North South South NorthQ South North North SouthR South North South NorthB. 3.0 A C. 6.0 A D. 24.0 A20. What is the power loss in the cable? A. 6 W 17. Which of the following can be use to determine the direction of magnetic field produced by current-carrying conductor? A. Lenz's law B. Faraday's law C. Fleming's Left-hand rule D. Right-hand Grip rule B. 12 W C. 18 W D. 24 W38JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismPart B: Structure Questions 1. Figure 1 shows an electromagnet connected to a 6.0 V d.c power supply.switch Insulated wire6.0 V dcDC supplypins Xa) (i) What is the core made of? Soft iron core (ii) State the po North b) When the switch is closed, it was found a number of pinway to decreasing the number of pins attracted to end X? Reduce the dc power supply to reduce current (ii) What will happen to the pins at end X er. Pins drop into the container. Soft iron core losses its magnetism 2. Figure 2 shows an alternating current generator.39JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: Electromagnetisma) (i) Name the phenomenon used to produced an e.m.f in the coil. Electromagnetic induction ...... (ii) What is the effect on the current produced if trt from each other? Give a reason. Current decreases. The magnetic flux becomes weaker. A lower rate of change of . magnetic flux results aCurrent, I/A 4 2 0.04 0.08 -2 -4 i. State the value of the peak current. 2A equency of the alternating current. f = 1 / 0.08 = 12.5 Hz .. iii. On the saaph output current against time if the coil is now rotated at twice the speed. c) What are the changes that need to be made to convert this generator to a direct current motor? Replace the slip rings commutator to a commutator. 40JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: Electromagnetism3. Figure shows a magnet which is pushed towards a solenoid.QPGalvanometer a) State the magnetic poles of the two ends, P and Q of the solenoid when the magnet is moved towards the solenoid, stationary inside the solenoid and then move away from the solenoid. Move toward P is North pole and Q is South pole, Stationary no pole for P and Q Move away P e.m.f is such that its magnetic effects always oppose bigger. The relative motion between magnet and coil is increased .. Teased ... The cross-sectional area of the coil is increased .41JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: ElectromagnetismPart C: Essay Questions 1. The transmission of electrical energy from a power station to factories and houses is by means of a system called National Grid Network. a) State the transformation of energy in a hydroelectric power station. b) Explain what is meant by National Grid Network and state three advantages of its distribution of electrical energy. c) Figure 4 below shows a model for transmission of electrical power using source of 12 V a.c.12 V a.c source240 V240 V12 V12 V bulb is brightTransmission wireYou are supposed to set up the model by using the information in the table below: Number of turns of coils 1200 600 60 40 Types of transformers Solid copper core Laminated soft-iron core Laminated copper core Wooden core Material of transmission cables Constantan Copper Nichrome Tungsteni. Choose the number of turns of primary and secondary coil for step-up transformer. Give a reason. ii. Choose the type of core of the step-up and step-down transformer. Give a reason. iii. Choose the type of material of transmission cables. Give a reason. d) If the resistance of the transmission cable in the model is 20 , calculate i. the current that flows through the transmission cable ii. the power loss due to heating effect of the transmission cable42JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: Electromagnetism1.a) Gravitational potential energy kinetic energy electrical energy b) -National Grid Network is a network of underground cables and pylons cover the whole country. -It enables the transmission of electricity to be distributed to various regions continuously. -If any breakdown, the electric can be supply from another areas from another pylons -It has good electrical energy consumption such as transferring the energy from low needed energy to high needed electrical energy c) i. 60:1200 because 60:1200 = 12:240 ii. Laminated soft-iron core because its easy to magnetized and demagnetized iii. Copper because it has smaller resistance and can reduce the power loss d) i. V=IR, I = 12 A ii. P = I2R = (12)2 (20) = 2880 W2. Diagrams show wire coils connected to the ammeters, switches and d.c power supplyWhen the switch is on and iron filings of the same amount is spread on each of the cardboard surface, the pattern of the iron fillings is formed as shown in the diagrams. a) What is meant by magnetic field? b) Using diagrams above, compare the number of turn of the coils, the pattern of the iron fillings and the angle of deflection of the ammeter indicator. 43JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: Electromagnetismc) State the relationship between the strength of the magnetic field and i. the pattern of iron fillings ii. the number of turn of the coils d) Diagram shows two thin copper strips, PQ and RS, connected via circuit. Explain what happens to PQ and RS, when the switch is on.PQ+_ Q S+_2 (a) Magnetic field : magnetic force region (b) The number of turns of the coil in Diagram 10.2 is more // vice versa The arrangement patterns of the iron fillings in Diagram 10.1 is further apart // vice versa. The angle of deflection Diagram 10.2 is bigger.(c) (i) - The closer the pattern og iron filling , the greater strength of magnetic field / vice versa (d) - When current flows, the magnetic field is formed // Diagram - The direction of the current in the thin copper : The flow of current is in the opposite direction // Diagram - The direction of magnetic field between two thin copper strips : same direction The two pieces of thin copper repulse against one another / diagram.44JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: Electromagnetism3. A student used the apparatus shown in figure below to investigate electromagnetic induction. The magnet will be drop inside the coil. He observed that the angle that the pointer of the galvanometer deflects become increase when he increase the number of turns on the solenoid.GGa) From the above observation, make a suitable inference b) State one appropriate hypothesis that could be investigated c) Design an experiment to investigate the hypothesis that you stated in (b). In your description, state clearly the following: i. Aim of experiment ii. Variables in the experiment iii. List of the apparatus iv. Arrangement of the apparatus v. Procedures of the experiment on controlling the manipulated and responding variables vi. Tabulation of the result vii. Analysis of the result viii. State one precaution in the experiment45JPN Pahang Teacher's GuidePhysics Module Form 5 Chapter 8: Electromagnetism3. e) Inference: The e.m.f induced in the solenoid influenced by the number of turns in the solenoid. f) Hypothesis: The e.m.f induced in a solenoid increases when the number of turn on the solenoid increases g) i. Aim: To investigate the relationship between the e.m.f. induced in a solenoid and the number of turns of the solenoid ii. Manipulated variable: Number of turns of the solenoid Responding Variable: e.m.f induced in the solenoid // Galvanometer reading Fixed Variable: The strength of the magnet used // the speed of magnet movement into the solenoid iii. Magnet bar, Galvanometer, copper wire iv. See above picture v. 1. Wind 50 turns of copper wire to make a solenoid, then connect to a galvanometer 2. Release a strong magnet bar from the top into the solenoid and take the reading of galvanometer 3. repeat the experiment using 100, 150, 200 and 250 turns of copper wire vi. Table of result Number of turns, N 50 100 150 200 250 vii. Analysis of results Galvanometer reading, V/divGalvanometer reading, V /divisionsNumber of turns / N46